I. Field of the Invention
This invention relates generally to a method and apparatus for cultivating turf and more particularly to a method and apparatus which utilizes the discharge of a high pressure fluid to cultivate and aerate turf.
II. Discussion of the Prior Art
Turfgrasses are utilized for functional, recreational and aesthetic purposes, including, but not limited to, the playing surfaces of turf facilities among them golf courses, parks, sports fields, cemeteries, highway rights of ways and industrial and home lawns. While this specification will discuss turf maintenance specifically with respect to golf course greens, it is to be understood that these maintenance problems exist with all turf surfaces.
Intensive use of a turf area and maintenance operations often result in turf wear and soil compaction. This compaction reduces large, or macro, pore space and total pore space in the soil which in turn reduces water infiltration into the soil, percolation through the soil, and drainage through the soil; limits exchange of soil gases, especially soil oxygen, with the atmosphere; and tends to restrict and reduce root growth and development of turfgrasses, for example, causing, in some cases, substantial reduction of the root system and often death of deeper roots.
The proper cultivation of turf to enhance drainage, and thereby thorough root growth, and improve the soil-air-water relationship has long been a problem within the industry, and a great number of devices have been proposed in the past in an effort to find a solution.
Core cultivation (aerification) is widely utilized as a long-term program to alleviate compacted conditions in the soil root zone. Several different types of core cultivation equipment are available commercially. One such type is the Toro Greensarator. Core cultivation equipment utilize vertically operating hollow metal tines which are forcibly driven into the turf to a depth of 21/2 to 3 inches to extract a plug, or core, of the turf which is then deposited on the turf surface of the green. (In some instances the cores are collected and removed from the green).
Research has shown that core cultivation creates a serious problem. Repeatedly forcing the metal tines into the turf to a common depth will, over time, create a compacted subsurface layer of soil, sometimes called plow sole, at a depth about one inch deeper than the length of the tines, in other words at about 31/2 to 4 inches below the surface of the turf. Further, the metal tines also tend to glaze the soil and create some compaction along the sides of the coring hole. This subsurface compaction creates two major problems with proper turf management. First, the compacted layer interferes with proper water movement within the soil, and second the compacted layer interferes with proper root growth of the turf grasses. In addition to the compaction problem, core cultivation creates another problem--the removal or utilization of the removed turf cores. Present techniques often leave a golf green unplayable for two to three days after treatment, The present invention provides a method and apparatus which will allow immediate turf and subsoil treatment at the time treatment is needed rather than waiting for a convenient time.
The present invention is a unique method and apparatus for accomplishing subsoil cultivation which utilizes periodic turf and soil injection of a substantially incompressible liquid, such as water, in a pattern, and at sufficient pressure, to lift and fracture the soil to reduce the compaction, or general density, of the treated area. There are numerous prior art disclosures which use incompressible liquids for turf treatment, however, none of these references teach or suggest subsoil cultivation through the use of liquid injection to reduce soil density.
Marron et al., U.S. Pat. No. 2,930,334 discloses an apparatus for injecting liquid compounds such as liquid fertilizers or weed killers into the turf to be treated. Marron '334 gives no indication of any jet pressures, nor does Marron suggest liquid injection for the purpose of reducing the general turf density. Indeed, Marron teaches the sequential operation of a series of liquid injection nozzles such that the pattern generated could not create a significant reduction in soil density.
Baldwin et al., U.S. Pat. No. 3,012,526 discloses a method for injecting liquids into soil by imparting, through the application of high pressure, a high velocity to a slug of liquid to cause the unconfined liquid slug to penetrate the soil. More particularly, Baldwin is directed to a method of injecting liquids such as soil fumigants, liquid fertilizers, and insecticides by jet penetration. Nothing in the Baldwin teaches or suggests the pressures or injection spacing necessary to significantly reduce the general density of the treated soil.
Johnston, U.S. Pat. No. 2,988,025, and its Reissue U.S. Pat. No. Re. 25,307 relate to methods of imparting highly volatile liquids, such as anhydrous ammonia, into soil for the purpose of fertilization or fumigation. Neither of the Johnston references teaches or suggests the utilization of pressurized liquid injection to reduce compaction, or in other words, to reduce the general soil density so as to improve drainage or turfgrass growth.
Johnston, U.S. Pat. No. 3,521,819 discloses a hydraulic device for intermittently injecting slugs of liquid under pressure into the soil. Johnston '819 is specifically described as an improved apparatus for carrying out the invention described in Baldwin, U.S. Pat. No. 3,012,526 discussed above. Nowhere does the '819 patent, either alone or in combination with the Baldwin reference, suggest a method or apparatus for reducing the general density of the soil in order to improve its drainage and thereby enhance root growth.
Collins, U.S. Pat. No. 3,926,131 and its continuation-in-part U.S. Pat. No. 4,034,686 disclose turf treating equipment which utilize liquid injection tongs, or tines, which are mechanically driven into the soil to be treated. Each of the tongs has a nozzle adjacent its tip so that liquid can be injected into the turf after the tong is buried in the turf. Neither of the Collins references teaches or suggests the injection of slugs, or jets, of liquid at a pressure and spacing sufficient to reduce the general density of the treated turf.
Russell et al., U.S. Pat. No. 4,009,666 discloses an apparatus for injecting liquids below the surface of the turf. The '666 patent describes the application of a continuous stream of liquid rather than the application of periodic slugs, or jets, of pressurized liquid. Nothing in the Russell patent teaches or suggests a method or apparatus for reducing the general density of the treated turf.
Johnston, U.S. Pat. No. 4,624,193 is directed to a method and apparatus for the jet injection of liquids into the soil. More particularly, the '193 reference pertains to the application of agricultural liquids to plants rather than the treatment of turf. Nothing in the Johnston '193 patent teaches or suggests either the pressures or pattern spacing necessary to accomplish a general reduction in soil density.
The present invention address the shortcomings of the above-noted devices and methods as they are utilized for cultivating turf and in particular golf fairways and golf greens. The previously discussed devices are not suitable for cultivating by means of only hydraulic pressure, turfs such as golf greens. In addition to being specifically designed for such purposes, the present device and methods also utilize several new features which provide for an improved hydraulic cultivator.
These features include applying mechanical pressure to the turf after the subsoil under the turf has been cultivated. The prior art devices did not address the problems associate with indentations which can be caused on turf after it has been cultivated. The prior art devices did not give consideration to the indentations which would be left by the wheels of the apparatus after the subsoil had been cultivated.
In addition, another feature of the present invention is a means for setting a first speed when in a transport mode and a second speed when in a cultivating mode. Still further, the speed control during the cultivating mode is constructed such that there is always the same set speed in a first direction as in the second direction, which is 180.degree. from the first direction. This provides for even hole spacing while the apparatus is being utilized in a bidirectional manner. Such features are not addressed by the prior art.
Still further, the apparatus provides for a valve which is able to have its valve seat concentric with the valve stem as well as controlling the timing of the flow through the nozzles between 0.007 to about 0.065 seconds. Such a feature is not addressed by the prior art.
Still further, Applicants have found that it is advantageous to utilize a water hammer effect in their apparatus. In doing so, they have discovered there is a relationship between the cross-sectional area of the bore and the accumulated area of the nozzle output ports. The prior art does not disclose taking advantage of this effect.